Paper 1 practice questions Flashcards
describe how the body protects against pathogens?
Skin physical barrier
Produces sebum oil which repels pathogens
Tears produce enzymes (lysosome) which repel’s pathogens
cillia and mucus which trap pathogens and move it up the throat to be coughed out
inside the body
Lympochytes create antibodies which kill pathogens
Hydrpochloric acid which kills pathogens
In a scientific experiment how could the method be improved for more valid results?
repeat and evalute the mean
How is the volume of water lost from the leaves controlled?
Opening and closing of the stomata
Describe the transport of water through a plant from the roots to the atomsphere
Absorbed through the roots via osmosis and transported through the xylem
water evaporates and leaves through the opening and closing of the stomata
explain why someone with a leaking heart valve would have difficulty while exercising
Valves control the flow of blood - leaky valve means a backflow of blood
Less oxygen is supplied to the muscles
body has to rely more on anaerobic respiration and the lactic acid will cause muscle fatigue
Evaluate the use of mechanical replacement heart valves and biological replacement heart valves?
mechanical
Longer lasting
May blood clot of surface of valve
Medication necessary as it could lead to excessive bleeding
Biological
No medication is needed
valve may harden
Name a chemical used to test for glucose
Benedicts
Name a test that could show a person’s urine contains glucose
Benedicts going from a blue to brick red
describe how diabetes can cause body cells to lose more water
Blood is more concentrated (with sugar ), water moves out of cells via osmosis, blood has a low concentration of water so more water will be lost from cells
describe how small intestine is adapted for efficient absorption
Large surface to volume ratio
easy access to many blood vessels
Many folds (walls of projection and villi which gives more surface area and short distance to diffuse
walls are only one cell thick
many mitochondria - more energy released
define the double circulatory system
Blood to the lungs by the right side of the body
blood to the body on the left side
Explain why having only one ventricle makes the circulatory system less efficent
Oxygenated and deoxygenated blood will mix
so less Oxygen will reach the tissues of the body
Why would an axolotl die in water with low oxygen concentration
Low oxygen concentration means that gills struggle to diffuse oxygen into the body, Body has to rely on anaerobic which produces toxic lactic acid
Name organs in the digestive system that produce carbohydrase
Salivary glands
small intestine
explain how pancreatic cancer may cause a person to lose weight
Body cannot create many enzymes , body must use more energy to break down food
less glucose absorped and less avaliable for respiration
why are double blind and placebo’s used in clinical trials?
Placebo - to stop the psycholgical effect of feeling better
and double blind to avoid bias
Monoclonal antibodies are produced to treat pancreatic cancer , how do they work to treat the cancer?
Monoclonal antiobodies is attached to radioactive substances
Monoclonal will only attach itself to the target cells , the toxin will drug tostop division of cancer cells
explain why the mass of eggs that been in water has increased (hint osmosis)
a)
Mass increased because water entered the cell by osmosis
Moved from an area of high to low concentration through a partially permeable membrane
Explain how a student could modify an investigation, to determine the solution inside of each egg b)
Changing the solution/solvent of the experiment
use a graph to plot the % change of results
explain how calcium ions are moved from the shell to the cytoplasm of the egg
The calcium ions move from an area of low to high concentration by active transport (use ATP energy)
An aphid eats by putting it’s mouth into the stem of a plant, the mouthpiece of the aphid now contains high concentrations of dissolved sugars explain why
mouth piece has bitten into the phloem which contains high amounts of dissolved sugars
How could a magnesium deficiency cause yellow leaves and stunted growth in a plant
Mg deficiency causes chlorosis which is a lack of chlorophyll -causes yellow leaves
less light is absorbed by the chlorophyll meaning less is used on photosynthesis
Plant makes less glucose so less glucose used to make amino acids = less growth
Farmer thinks his crops are infected with PVY virus how would you create the PVY monoclonal antibodies
First isolate the PVY proteins from the virus
inject this proteins into a mouse combine the lymphocytes from the mouse with fast reproducing tumor cells to make the hybridoma cell
this hydridoma cell can make antibodies but can also reproduce quickly like tumor cells
Used to make the antibodies specific to the PVY proteins (specific to the PVY antigen) and can be cloned
describe how a student could test cow’s milk to show whether it contains proteins and different types of carbohydrates
for protien
Use biurets solution turns from blue to purple if positive for protien
For carbohydrates
use iodide turns black/blue if positive
For sugars
Use benedicts add a few drops to the milk and boil
the solution will turn from blue to brick red
Why is bile rapid at breaking down fats?
the bile emulsifies fats (breaks down fats from large droplets to smaller droplets) creating a larger surface area so lipase is broken down fats to produce fatty acids + glycerol more quickly
why is there more antibiotic resistant strains of bacteria?
Due to antibitoics killing non-resistnat strains leading to less competition to multiply
overuse of antibiotics and people not finishing antibiotic course?
How does a vaccine make someone immune to a disease?
This is through the vaccine stimulating antibodies
by white blood cells
to rapidly reproduce on re-infection
